The aw of the syrup was measured in duplicate with an AquaLab Series 3 water activity meter (Decagon Devices, Pullman WA) according to the manufacturer's instructions. Certified water activity standards with aw values of 0.760 ± 0.003 (6.00 mol/kg NaCl) and 1.000 ± 0.003 were obtained from the manufacturer. The estimated sugar content as °Brix was determined by two techniques
used by maple syrup producers. Except for the cases where there were mold-damaged samples, the readings were taken in all three remaining samples.